1. Field of the Invention
The present invention relates to hydraulically and volumetrically dispensing fluid. More particularly, the present invention relates to systems and methods for dispensing a known volume of a target fluid, whether liquid and/or gas, through the use of a hydraulic system.
2. Background and Related Art
Historically, a variety of techniques have been employed to dispense materials. Such techniques have included pushing a material through a flexible conduit, using a water control valve to provide pressure to a material, employing a water control valve to dispense the material, and using a hand-held applicator that accommodates a syringe, each of which will be discussed below.
A first technique employs a flexible conduit through which a material is pushed. In U.S. Pat. No. 5,878,921, a grout delivery apparatus and method is disclosed for delivering grout through a flexible conduit from a bulk supply of grout to a hand tool. The bulk supply of grout is held in a hopper, which feeds the grout under gravity to a pump. The pump is driven by an electric motor, which receives its electrical energy through a controller. The controller is adjustably preset to control the electric motor as a function of the individual settings on a malfunction switch operable by the worker. The switch can either be mounted on the hand tool and directly wired to the controller or incorporated into a remote transmitter, which transmits the particular switch position to a receiver on the controller. Similarly, U.S. Pat. No. 6,268,000 discloses a device for dispensing pastry dough, frosting, or icing from a cartridge. The device has a cartridge container and a hand-held gun. An electric motor having a piston is coupled to the cartridge container. The piston acts on a plunger of the cartridge to apply pressure on the pastry dough, frosting, or icing to permit the pastry dough, frosting, or icing to move to the gun to be dispensed. The technique in both disclosures requires a material to be pushed through a tube or flexible conduit in order to dispense or apply the material. One disadvantage of this technique is that residue of the material is typically left behind on the inside wall of the tube or conduit that must be cleaned. This requirement of cleaning the tube or conduit can be time consuming and the residue indicates a waste of a portion of the material.
In a second technique, a water control valve is employed to provide direct pressure to a material that is being dispensed. This technique is disclosed in U.S. Pat. No. 6,041,977, which discloses a dispensing system for dispensing decorating materials, such as frosting. The dispensing system includes a dispensing tube having the material to be dispensed and a water-operated piston. Application of water under pressure to the dispensing tube results in the dispensing of the material through a decorating tip. The water pressure applied to the dispensing tube is controlled and regulated through the utilization of a control valve assembly having a flow stop valve and an on/off valve. Water applied to the control valve assembly is pressure regulated and filtered. While this technique reduces the requirement for cleaning and reduces the amount of material wasted, it requires the constant pressurizing of water and typically proves to be awkward in use of some applications.
A third technique employs compressed air to dispense a material. This technique illustrated in U.S. Pat. No. 5,964,381, in which a piston is disposed inside a tube having an inner cross-sectional size and shape uniform along its length. The tube has an open end. The piston is free to move literally inside the tube and preferably may move out of the tube through the open end. If the tube is cylindrical in shape it has a constant inner diameter. The open end of the tube is neither tapered nor flaring. Liquid samples are aspirated into the device by pulling the piston back. The sample is then ejected by accelerating the piston to a minimum velocity to force the liquid sample out of the open end of the tube. The velocity of the sample is sufficient to render negligible effects of surface tension forces. The volume of the liquid sample dispensed is determined by the inner diameter of the tube and the piston displacement. Accurate positioning of the piston provides samples of accurate volumes. This technique can provide an accurate delivery of a material as long as the viscosity of the air does not change. However, a change in atmospheric temperature and/or pressure affects the technique by requiring the system to be adjusted for each given atmospheric modification. As such, this technique can prove to be time consuming, as it requires the calibration to the various surrounding conditions.
Another technique is provided in U.S. Pat. No. 5,630,527, which discloses a fluid dispenser system, and method of use thereof, primarily in industrial applications requiring the dispensing of fluids, such as epoxies, silicones, adhesives, etc., allowing for very precise control of the volume of fluid extruded. The system comprises an ergonomic, hand-held applicator accommodating a conventional medical syringe, wherein the applicator is attached to an electronic control unit by a power cord. The applicator is provided with a stepping motor that drives a piston or screw a specific distance in response to an electronic signal generated by the control unit. Displacement of the piston or screw creates a positive pressure on a fluid contained in the syringe, thereby causing fluid extrusion from the syringe. While this technique can dispense a precise amount of material, the apparatus of the hand-held applicator can prove to be bulky and awkward to use.
Thus, while techniques currently exist that are used to apply or dispense a material, challenges still exist, including causing a portion of the material to be wasted, needing to clean the residue from the material after each use, requiring a calibration of the device for each surrounding condition, and other such challenges. Accordingly, it would be an improvement in the art to augment or even replace current techniques with other techniques.
The present invention relates to hydraulically and volumetrically dispensing fluid. More particularly, the present invention relates to systems and methods for dispensing a known volume of target fluid through the use of a hydraulic system. As used herein, xe2x80x9cknown volumexe2x80x9d means a metered controlled predeterminable quantity of fluid or in some embodiments a predetermined quantity of fluid which has a controlled volume or quantity such as a bolus.
Implementation of the present invention takes place in association with a target fluid, whether in a liquid and/or gaseous state, that is to be dispensed. A hydraulic system is configured to selectively provide mechanical pressure in order to dispense a volumetric or metered dose of the target fluid from a container, syringe, etc., which includes a slidable or movable plunger or wall that when moved forces the target fluid out of the container or syringe or draws substances into the container or syringe.
In one implementation, a dispensing system includes an actuator, such as a motor or driver, a hydraulic coupler, column or tube that includes substantially incompressible hydraulic liquid, and a mechanical interface to the container or syringe. The actuator may comprise a motor or driver, such as a step motor, linear actuator, servomotor, pneumatic motor, or other similar device, to drive a plunger or piston of the hydraulic coupler. The coupler includes a conduit, column, shaft or other leakproof assembly that acts as a conduit for the substantially incompressible hydraulic liquid. The conduit is connected at one end to a plunger/piston and at the other end to a mechanical interface. The mechanical interface includes a cylinder structure with another plunger or piston that is selectively pushed by the incompressible hydraulic liquid, thereby driving a head of the plunger or piston to press against the wall or plunger of the container or syringe that contains the target fluid, causing the target fluid to be dispensed therefrom. Thus, an actuator selectively provides a force on the hydraulic coupler, which transfers the force to the target fluid to dispense the target fluid from the container. In one implementation, a controller or computer device is coupled to the actuator to accurately dispense a volumetric amount of the target fluid.
While the methods and processes of the present invention have proven to be particularly useful in the area of dispensing a precise amount of target fluid, those skilled in the art can appreciate that the methods and processes can be used in a variety of different applications and in a variety of different areas of manufacture and/or industry to accurately dispensing a volumetric amount of fluid.
These and other features and advantages of the present invention will be set forth or will become more fully apparent in the description that follows and in the appended claims. The features and advantages may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. Furthermore, the features and advantages of the invention may be learned by the practice of the invention or will be obvious from the description, as set forth hereinafter.